Plastic fenestration product

ABSTRACT

A fenestration product such as a skylight or a window assembly is provided having a frame with a peripheral wall with a light transmitting central region and a plastic dome formed of a light transmitting material mounted to the frame. The plastic dome has a central region which transmits light, a downwardly extending peripheral wall extending about and mounted to the peripheral frame, and an outwardly extending flashing flange for mounting the assembly to a building structure. Various embodiments of the part illustrated include a skylight assembly having a frame formed of a plastic layer formed into an inverted “U” shape cross-section forming an annular channel filled with insulating foam. A sealed, vertically mounted window unit is also disclosed. Other embodiments have an insulating layer of transparent plastic material spaced from the dome forming an enclosed, gas filled insulating region. Methods of forming and installing a fenestration assembly are also described.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to fenestration products composed primarily of plastic.

2. Background Art

Plastic is used in a variety of fenestration products such as skylights and windows in buildings as an alternative to a glass panel. Plastic and glass fenestration panels each have their respective advantages and disadvantages. Glass is relatively inexpensive, has good optical properties, is scratch resistant and stable in a variety of harsh environments. Glass, however, is relatively heavy, susceptible to catastrophic failure and can be difficult to handle and fabricate. There is a wide a variety of plastics available for use in fenestration products. Some are low cost, tough, readily formable and environmentally stable. Many plastics, however, are susceptible to scratching, lose their physical properties with age or exposure to environmental factors, and can be relatively expensive.

The use of plastic and fenestration products, although a very small portion of the market compared to glass, is still quite significant. Plastic panels are used in doors for example, particularly storm doors to minimize the risk of injury due to glass fracture. Acrylic dome panels are used in both residential and industrial building skylights, as illustrated in U.S. Pat. Nos. 3,434,257; 4,514,944, and 4,344,261. Recently, the plastic dome skylight has been introduced having acrylic dome mounted in a polyurethane frame molded in situ about the dome peripheral edge, as illustrated in published U.S. patent application 2005/0178078, illustrated in website, www.vtechindustries.com/products.html and available from Vtech Industries, Inc. and Carlisle SynTec, Inc.

The focus of the development efforts in the plastic fenestration product area has been, how to mount the plastic panel to the building opening in a secure leak proof manner, while securely supporting the plastic panel on a frame or curb in a structural manner. Many of the mounting systems are comprised of multiple component parts which require assembly and have joints which are susceptible to water leaks. Some skylights are deck mounted, others use raised curbs. The molded polyurethane frame of the VTech™ skylight is a simple one piece molded structure which is securely bonded to the plastic dome in a leak proof manner resulting in a very high performance skylight. This skylight, however, is expensive to manufacture as the tooling and production equipment needed is costly and the raw material cost of the high performance polyurethane utilized prevents this construction system from being used in low price point skylight applications.

SUMMARY OF THE INVENTION

Accordingly, one of the benefits of the present invention is to develop a low cost fenestration product which is suitable for use in skylights or the like which can match the state of the art water intrusion standards set by the in situ molded polyurethane frame systems. It is a further advantage of the invention to develop a fenestration product which is relatively inexpensive to manufacture and requires minimal investment in capital equipment.

The fenestration product made in accordance with an embodiment of the present invention includes two main components; a frame and a plastic dome formed of a transparent material which is mounted to the frame. The dome has a central region which transmits visible light and a downwardly extending peripheral edge which extends about the peripheral wall of the frame. The dome is further provided with an outwardly extending flashing flange for mounting the assembly to a wall of a building structure surrounding a building opening.

In one embodiment of the invention, the frame comprises the unitary plastic ring having a central opening formed therein. The frame peripheral wall is preferably formed of an inverted “U” shape cross-section having an outer peripheral wall cooperating with the plastic dome and an inner peripheral wall aligned with the building opening upon which the fenestration product is mounted.

The invention further includes the method of manufacturing a fenestration product. The method includes the steps of thermoforming a first plastic sheet into a ring shape frame having a generally “U” shaped cross-section formed by an outer peripheral wall. A second plastic sheet formed of a material capable of transmitting visible light and is thermoformed into a dome having a central portion and a downwardly extending peripheral wall cooperating with the outer peripheral wall of the ring shape frame. The ring shape frame and dome are joined in a nested manner with the dome downwardly extending peripheral flange cooperating with the frame outer peripheral wall, where at least one of the ring shape frame and dome is formed with an integral outward extending flashing flange suitable for mounting the assembly on the building structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first skylight embodiment of the invention;

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1;

FIG. 2 a is a cross-sectional view of an alternative embodiment of the FIG. 1 skylight;

FIG. 2b is a cross-sectional view of a second alternative embodiment of the FIG. 1 skylight;

FIG. 3 is a cross-sectional side elevation of a light pipe alternative embodiment of the invention;

FIG. 4 is a side view of a window assembly embodiment of the invention;

FIG. 5 is a cross-sectional plan view taken along line 5-5 of FIG. 4;

FIG. 6 is an exploded cross-sectional side elevation taken along line 6-6 of FIG. 4;

FIG. 7 is a top view of a window assembly embodiment of the invention; and

FIG. 8 is an exploded cross-sectional top view of a window assembly embodiment as illustrated in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for the claims and/or as a representative basis for teaching one skilled in the art to utilize the present invention.

Except where expressly indicated, all numerical quantities in this description indicating the amounts of material or conditions are understood as modified by the word “about” in describing the broadest scope of the present invention. Practice within the numerical limits is generally preferred.

Accordingly, a number of representative examples of the present invention are illustrated in the drawings and described herein. In the first example, skylight assembly 10 is illustrated in FIGS. 1 and 2. Skylight 10 has two main components as best seen in the FIG. 2 cross-sectional view illustrating the skylight mounted to an opening in a building roof 12. The skylight includes a dome member 14 and a frame member 16 which are both formed of sheets of plastic which have been thermoformed to a three dimensional shape using a conventional thermoforming process such as vacuforming, twin-sheet thermoforming or pressure assisted sag forming. Dome 14 is preferably formed of a light transparent and plastic material such as acrylic or polycarbonate. Depending on the application, the dome may be transparent or may be translucent. A translucent layer having a whitish color can allow light to pass through and act as a diffuser. Plastic dome 14 has a central panel 18 forming a dome shape, a downwardly extending peripheral wall 20 and an outwardly extending flashing flange portion 22. Dome 14 is secured to a peripheral wall portion 24 of frame 16. Frame 16 is also thermoformed of a plastic sheet with the peripheral outer wall 24 forming an annular ring to support dome 14. The frame 16 defines a light transmitting central region 26 to allow light passing through the dome 14 central panel 18 to freely enter the building roof 12.

In the first embodiment of the invention illustrated in skylight assembly 10, the frame 16 has a peripheral wall portion which in cross-section forms an inverted “U” shape having an inner wall portion 28 and upper wall 30. Extending radially outward from outer peripheral wall 24 is a flashing flange 32 which underlies flashing flange portion 22 of dome 14. Optionally, inner peripheral wall 28 extends downwardly into the building slightly below the level of the flashing flange 32 as illustrated in FIG. 2 in order to help align the skylight with the opening formed in the roof sheathing 34. Frame 16 may be formed of a different plastic material than the dome 14 since transparency is not required in the illustrated embodiment. The frame plastic material is preferably of a material which can easily be bonded to the frame using conventional adhesives, solvents or weldments. In the embodiment illustrated, the cavity formed within the inverted “U” shaped cross-section of frame 16 is filled with a foam insulation material 36.

In a typical 2′×4′ building opening size application, skylight 10 can be manufactured using a dome formed of acrylic having a wall thickness prior to thermoforming of 0.60 inches to 0.236 inches or the wall thickness capable of supporting an ultimate load needed in service or required by a regulation or an architect. These ultimate loads may include in excess of 20, 40, or 60 pounds per square feet as tested using procedure A of ASTM E330 after stabilization according to procedure A of ASTM D618. The frame may be formed of acrylic or a different plastic material such as acrylic polycarbonate, terephthalate, polyoxymethylene, polyolefin, and/or polyvinylchloride, since light transmission is not an issue. The wall thickness of the frame need not be thick, particularly when the frame filled with a rigid insulation foam 36. A wall thickness of the frame can range from 0.030 to 0.236 inches. Foamed insulation material such as polyurethane, expanded polystyrene, or polyisocyanurate can be used having densities between 1 pound per cubic foot and 40 pounds per cubic foot.

Preferably, the outwardly extending flashing flange 22 extends outwardly from a downwardly extending dome peripheral wall 28 at least 2″ to 9″ and more preferably, 3″ to 7″, in order to provide an adequate overlap to bond to the water barrier 38 mounted to the building sheathing 34 to allow adequate overlap with the roofing material 40 to prevent water leakage into the building opening. Flashing flange 22 also serves as a mounting flange for attaching the skylight assembly to the building roof sheathing 34. Preferably, corrosion resistant screws or nails are installed through the flashing flange portion 22 into the building roof sheathing 34. The mounting fasteners are preferably located significantly outboard of the dome downwardly extending peripheral wall 20 and well inboard of the outer peripheral edge of the mounting flange, but not necessarily aligned in a row, in order to minimize stress concentrations in the mounting flange caused by wind load on the skylight dome 18. Ideally, holes for fasteners do not have to be pre-drilled, that way assuring that any unused fastener holes do not provide an entry leak path for water. Holes for fasteners 42 may be drilled at the job site. In order to minimize screw pull out, the screws are preferably provided with a relatively large low profile head or be provided with an associated washer such as a compression washer.

FIG. 2 a illustrates a cross-sectional view of an alternative embodiment of the skylight assembly. Skylight 44 is made up of three main components; a dome 46, a frame 48 and an insulating layer 50. Dome 46 and frame 48 are substantially similar to dome 14 and frame 16 described in reference to the embodiment invention of FIG. 2, except that the frame 48 terminates before the region in which fasteners are inserted. Insulating layer 50 is formed of a light transparent plastic material. Insulated layer 50 has a central region able to transmit visible light and an outer peripheral flange which is mounted to one of the dome 46 or frame 48 in order to define enclosed interior space 52 interposed between the central regions of dome 46 and insulated layer 50. Interior space 52 is filled with a gas such as air or argon and provides a relatively high thermal transmission resistant barrier between the interior of the building and the building exterior. Insulated layer 50 may be bonded to the upper most portion 54 of frame 48 with an adhesive material or weldment in order to bond the dome to the frame as illustrated. Preferably, one of the top region of frame 54 or the outer peripheral edge 56 of insulated layer 50 is provided with a groove 58 as illustrated for retaining a bead of adhesive or sealing material used to bond the insulated layer 50 to the frame 48. After the insulated layer 50 installed on the frame, the dome is attached using adhesives as described previously to form a completed assembly.

Yet another variation of the skylight assembly is illustrated in FIG. 2b. Skylight 62 is made up of a dome 64, a frame 66 and two insulating layers 68 and 70. Insulating layers 68 and 70 are preferably thermoformed into a dome shape and are formed of a light transmitting plastic material. When completely assembled, a first enclosed space 72 is defined between the dome and insulating layer 70 while a second adjacent enclosed space 74 is defined between insulating layers 68 and 70. These two isolated insulating spaces further enhance the thermal characteristics of the skylight assembly. Preferably, the frame 66 is provided with the pair of step annular recesses 75 and 77 to align insulating layers 68,70 within the assembly and provide a surface on which to secure the insulating layers 68 and 70. With reference to the insulating layers 50, 68 and 70 of skylight assembly 44 in FIG. 2 a and skylight 62 in FIG. 2b, respectively, the insulating layers 50, 68 and 70 can be made of relatively thin material since the layers are not subject to a significant mechanical loading. Material such as acrylic, polycarbonate, terephthlate, polyoxmethylene, polystyrene, and/or polyvinyl chloride may be utilized for insulating layers and the material thicknesses can be as thin as 0.030. A sealing bead 73 may optionally be attached to the frame 66 to provide a water resistant bed of sealant between the roof and frame 66.

FIG. 3 illustrates a domed skylight 76 which is part of a larger, tubular skylight assembly 78. Skylight 76 is made up of a dome 80, a frame 82 and an insulating layer 84 which defines an enclosed space 86 between the insulating layer 84 and dome 80. The upper portion of frame 82 forms an annular trough 88 which serves to trap condensate forming on the inner surface of insulating panel 84. Trough 88 prevents condensate from forming on the skylight interior and dripping into the building interior space. Trough 88 is sufficiently large so that the condensate would be collected during periods of condensate formation and subsequently evaporated when the humidity and/or temperature changes sufficiently to cause the condensate to evaporate. The tubular skylight assembly 78 includes the skylight assembly 76 as well as a light pipe 90 and light diffuser panel 92. Light diffuser panel 92 is mounted to the ceiling of a room within the building and the light pipe 90 extends between the diffuser and skylight assembly 76 to carry light from the skylight dome 80 through the light reflective interior surface of light pipe 90 into the room via the light transparent diffuser 92. Light pipe 90 can be made of a flexible conduit as illustrated or a sheet metal duct structure.

FIGS. 4-6 illustrate a different type of fenestration product constructed in accordance with the teachings of the present invention, namely, a window assembly 100. Window assembly 100 is adapted for permanent installation in a building opening such as a window into a building basement, crawlspace, or a fixed window in a garage, a garage door, or an entry system. Window 100 is specifically designed to simulate a glass block window commonly seen in building basements. Other textures may be incorporated as desired, such as a texture simulating camed glass. As illustrated in the FIG. 5 cross-sectional view, the window assembly 100 includes a dome 102, a frame member 104 structure and an interior layer 106 all formed of a thermoformed plastic material which transmits visible light. Dome 102 has a central panel portion 108, an outer peripheral wall 110 and an outwardly extending flashing flange 112. Frame 104 is also formed of a transparent plastic material having an outer peripheral wall portion 114 and a transparent central wall portion 116. The frame 104 is further provided with an outwardly extending flashing flange 118 overlying flashing flange 112 of the dome 102. Interior layer 106 is provided and bonded to frame 104 thereby defining two enclosed interior spaces between interior layer 106 and the central panel 108 of dome 102. First enclosed space 120 is interposed between interior layer 106 and frame central wall portion 116 and second enclosed region 122 interposed between transparent central wall portion 116 and the central panel portion 108 of dome 102. All three components; dome, frame and interior layer 102, 104 and 106 are forms of visible light transmitting thermoplastic sheet thermoformed to the desired shape. The panels are then joined together to form a secure assembly. Examples of joining methods may include, but are not limited to, ultrasonic welding, heat staking, and/or adhesives. It is understood that joining may also include fastening the three components 102, 104 and 106 to the building with screws, staples, nails or similar mechanical fasteners.

In the window assembly embodiment illustrated in FIGS. 4-6, the central panel 108 and interior layer 106 are provided with simulated grout lines 124 molded into the panels. Preferably, the remainder of the visible portion of panels 108 and 106 are provided with a textured pebble-like surface simulating the appearance of glass block. To further provide a visible barrier, the frame 104 may be formed of a translucent plastic material allowing light to pass, but, impeding the person's view through the window.

Window assembly 100 can be manufactured in standard basement window sizes. Windows can alternatively be designed to be mounted from the exterior or mounted from the interior of the building depending upon the architect's specification. The window assembly 100 can be attached to the wood framed window opening with conventional fasteners such as screws and nails. One or more bezels 126 may likewise be utilized either on the building exterior, building interior or both in order to further seal the joint between the building opening and the window assembly and to enhance the aesthetic appearance of the window.

The plastic sheets utilized to fabricate the three panels 102, 104 and 106 forming window assembly 100 may be of a variety of materials as described previously. While the frame material can be relatively thin, the panel facing the exterior of the building should be sufficiently thick to provide adequate security and provide acceptable aesthetic appearance. The plastic sheets may also be formed of composite sheets of plastic to provide desired enhancements. Examples of the composite sheets may include UV and/or heat transfer resistant films sandwiched between acrylic plastic. Another example may include an intrusion-resistant mylar film bonded between two thin sheets of polycarbonate plastic. It should be further appreciated that additional thin layers of thermoformed plastic material may be utilized in fabricating window 116 placed between dome 102 and inner layer 106 to increase the number of enclosed zones within the window to further improve the thermal resistance of the assembly.

Referring to FIGS. 7 and 8, these figures illustrate an alternative embodiment of a window assembly 130 in accordance with the teachings of the present invention. Window assembly 130 is adapted for permanent installation into a building opening such as window into a basement in a concrete block construction house member. As illustrated in the FIG. 8, an exploded top cross-sectional view, the window assembly 130 includes a dome 132 positioned in an opening in the concrete block wall section 134. The dome has a central panel 136, a peripheral wall 138 and a peripheral flange 142. The window assembly 130 is shaped like a top hat, and defines a cavity 146 into which an interior layer 148 may be inserted. The interior layer 148 includes a central wall panel 150 and a peripheral flange 152. The interior layer 148 may be inserted into the cavity 146 with the distal ends 140 of the flange 152 pointed toward the center panel 136 of the dome 132. It is understood that the distal ends 140 of the flange 152 may be directed away from the central panel 136 without exceeding the scope of this invention. The flange 152 may vary in size based on the number of inserts desired. Typically, the flange 152 may range in length from 0.25 to 4.0 inches and preferably 0.5 to 2.0 inches.

As an option, a sealed insulating unit 156 may be inserted adjacent to the interior layer 148. The sealed unit 156 may include a first central panel 158, a second central panel 160, a peripheral flange 162. The first central panel 158 is hermetically sealed to flange 162 creating an enclosed air space 166. Alternatively, a gas may be injected to space 166 to improve the thermal transmission resistance of the sealed unit 156. An example of the gas that may be injected is an insulator like argon. Alternatively, other insulators may be in the sealed unit. The insulator may include a vacuum, an aerogel, or a nanogel. The cavity 166 should be less than 0.625 inches in thickness and preferably less than 0.5 inches in thickness in order to prevent creation of convection cells within the cavity. The convection cells increase heat transmission. It is desirable that the flange 162 be less than 1.25 inch in length so that when placed adjacent to the interior layer 148, that they form a second air space 168 that may improve the thermal transmission resistance of the window assembly 130. Optional additional interior layers such as a second interior layer 170 may be inserted into cavity 146 to further improve the thermal transmission resistance of the window assembly 130. A coating, a deposition or a film may be applied to at least one of the components of the window assembly 130 including the dome 132, the interior layer 148, the sealing unit 156, and the second interior layer 170.

A cap 172 opposes the central panel 136 and provides closure to the cavity 146. The cap 172 has a peripheral flange 174 which is adjacent to the flange 142 of the dome 136. The cap 172 may also have positioning ribs 178 to assist in centering the cap in the opening in flange 142. The window assembly 130 including the dome 132 and the cap 172 are fastened to the concrete wall structure 134 using fasteners known in the art. An example of the fastener is a molly anchor 180. For aesthetic purposes, an interior trim bezel 182 may be attached to the cap flange 174 using a double stick transfer tape 184. It is understood that other means of attaching the interior trim bezel 182 that are known in the art may be used without exceeding the scope of the invention. Likewise, an exterior trim bezel 186 may be attached to the exterior of the concrete block structure 134 using a barbed insert 188. An example of the barbed insert 188 is commonly referred to as a “Christmas Tree”. It is understood that the barbed insert 188 may have individual prongs or be part of a more continuous ridge of barbed inserts. The window assembly 130 may optionally be insulated by injecting a foamed sealer 190, such as a foaming polymer like foamed polyurethane into a gap between the dome 132 and concrete block wall section 134 before application of the bezel 186.

The invention further includes a method of forming a fenestration product assembly. The method includes steps of thermoforming a first sheet of plastic into a ring shape frame having a cross-section and the general shape of an inverted “U”. A plastic dome is thermoformed from a second sheet of plastic material which transmits visible light defining a dome having a central region and a downwardly extended peripheral flange and a flashing flange extending outwardly from the outer peripheral wall. In one preferred embodiment of the method the central portion of the ring shape frame is cut out forming a central opening through which light can pass. The ring shaped frame and dome are then joined in a nested manner with the dome downwardly extending peripheral wall cooperating with the outer frame peripheral wall. Alternatively, the flashing flange may be omitted from the dome and provided on the ring shaped frame or flashing flanges may be included on both the dome and the ring shape frame.

The method of forming the fenestration product further includes the step of forming a transparent or translucent insulating layer which is interposed between the frame and the dome and bonded to at least one of the frame and the dome to define an enclosed space between the insulating layer and the dome to increase the thermal resistance value of the assembly. Alternatively, the method may include forming a second insulating layer interposed between the first insulating layer and the dome in order to define two separate enclosed regions between the dome and the two insulating layers to further increase the thermal resistance value of the assembly. It is understood that enclosed regions may include ventilating holes to allow relatively small transfers of gas to relieve pressure differentials or other issues associated with a sealed chamber exposed to temperature extremes.

The method may further include the step of filling the “U” shaped channel formed in the frame with the insulating material, such as a polymer foam which is preferably cured in place to substantially fill the “U” shaped trough defined by the frame.

While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. 

1. A fenestration product assembly comprising: a frame having an upwardly extending peripheral wall portion defining a light transparent central region; and a dome formed of a plastic material which transmits visible light, the dome mounted to the frame and having a central panel portion overlying the frame central region, a downwardly extending peripheral edge which extends about the frame peripheral wall, and an outwardly extending flashing flange for mounting the assembly to a building structure.
 2. The fenestration product assembly of claim 1 wherein the frame comprises a unitary plastic ring portion having a central opening.
 3. The fenestration product assembly of claim 2 wherein the frame peripheral wall portion has an inverted U-shaped cross section.
 4. The fenestration product assembly of claim 3 wherein the frame further comprises a thermal insulation material which substantially fills the inverted U-shaped cross section of the frame peripheral wall portion.
 5. The fenestration product assembly of claim 4 wherein the thermal insulation material comprises a polymeric foam material which is formed in situ.
 6. The fenestration product assembly of claim 3 wherein the frame further comprises a flashing flange portion extending outward from the wall portion and at least partially underlying the flashing flange of the dome.
 7. The fenestration product assembly of claim 1 further comprising an insulating layer formed of a plastic material which is transparent to visible light, the insulating layer mounted to at least one of the frame and the dome, and having a central panel portion overlying the frame central region and a peripheral edge which is mounted to at least one of the frame peripheral wall and the dome to define an enclose cavity between the insulating layer and the dome.
 8. The fenestration product assembly of claim 7 further comprising a second insulating layer formed of a plastic material which is transparent to visible light, the second insulating layer mounted between the insulating layer and the dome, and having a central panel portion overlying the frame central region and a peripheral edge which is mounted to at least one of the frame peripheral wall, the insulating layer and the dome, thereby subdividing the enclosed cavity between the insulating layer and the dome.
 9. The fenestration product assembly of claim 7 wherein the frame peripheral wall portion has an inverted U-shaped cross section.
 10. The fenestration product assembly of claim 9 wherein the frame further comprises a thermal insulation material which substantially fills the inverted U-shaped cross section of the frame peripheral wall portion.
 11. The fenestration product assembly of claim 1 wherein the frame comprises a unitary plastic ring portion and a light transmitting panel oriented in the frame central region in spaced apart relation to the dome central panel portion forming an enclosed cavity there between.
 12. The fenestration product assembly of claim 11 further comprising an exterior panel formed of plastic material having a light transmitting central portion overlying and spaced from the frame central region forming a second central cavity there between.
 13. The fenestration product assembly of claim 12 wherein the exterior panel is formed of a translucent plastic material have embossed thereon selected from a group consisting of a simulated glass block pattern and a camed glass pattern.
 14. The fenestration product assembly of claim 11 wherein the light transmitting panel further comprises a peripheral flange overlying and affixed at least indirectly to the dome peripheral flange.
 15. A fenestration product assembly comprising: a plastic ring shaped frame having an inverted U-shaped cross-section defining a central opening and an outer peripheral wall portion; and a dome formed of a plastic material which transmits visible light, the dome mounted to the frame and having a central panel portion overlying the frame central region, a downwardly extending peripheral edge which extends about the frame peripheral wall; wherein at least one of the frame and dome is further provided with an integrally formed outwardly extending flashing flange for mounting the assembly to a building structure.
 16. The fenestration product assembly of claim 15 wherein an upper region of the frame is provided with an integrally formed trough for collecting condensate forming on an interior surface of the assembly spanning the central opening in the frame.
 17. The fenestration product assembly of claim 15 further comprising an insulating layer formed of a plastic material which transmits visible light, the insulating layer having a peripheral edge which is mounted to the frame and a central panel portion overlying the frame central opening forming an enclosed cavity between the insulating layer and the dome.
 18. The fenestration product assembly of claim 17 further comprising a secondary insulating layer formed of a plastic material which transmits visible light, the secondary insulating layer mounted between the insulating layer and the dome, and having a central panel portion overlying the frame central opening and a peripheral edge which is mounted to at least one of the frame, the insulating layer and the dome, thereby subdividing the enclosed cavity between the insulating layer and the dome.
 19. The fenestration product assembly of claim 18 wherein the frame further comprises a thermal insulation material which substantially fills the inverted U-shaped cross section of the frame.
 20. A method of forming a fenestration product assembly, the method comprising: thermoforming a first sheet of plastic into a ring shape frame having an inverted U-shaped cross section with an outer peripheral wall portion; thermoforming a second sheet of plastic material which transmits visible light into a dome having a domed central panel portion and a downwardly extending outer peripheral wall; joining the ring shaped frame and dome in a nested manner with the dome downwardly extending peripheral wall cooperating with the frame outer peripheral wall portion; wherein at least one of the frame and dome is formed with an integral flashing flange extending outwardly from a bottom edge of the outer peripheral wall for mounting the assembly to a building structure.
 21. A fenestration product assembly comprising: a dome formed of a first plastic material which transmits visible light, the dome having a first central panel, a peripheral side, and a peripheral flange attached to the side, the side and central panel defining a cavity; an interior layer of a second plastic material which transmits visible light, the interior layer having a second central panel and a peripheral rib perpendicular to the second central panel, the interior layer being nested within the cavity and providing a first barrier to thermal transmission through the fenestration product; and a cap of a third plastic material which transmits visible light, the cap having opposed aligning ribs perpendicular to a third central panel, the aligning ribs engaging the dome to connect the cap to the dome.
 22. The fenestration product assembly of claim 21, further comprising: a sealed insert of a fourth plastic material which transmits visible light nested in the cavity, the sealed insert having a fourth center panel, a sealing sheet and a peripheral flange, the sealing sheet being connected to the flange of the sealed insert at a distance of less than 0.625 inches from the fourth center panel forming a chamber between the sealing sheet and the flange and capable of retaining an insulator within the chamber.
 23. The fenestration product assembly of claim 22, wherein the flanged sealed insert is adjacent to the interior layer, defining an unsealed chamber between the sealing insert and the interior layer, the unsealed chamber having a thickness of less than 0.625 inches.
 24. A method of installing a fenestration product assembly to a building, the method comprising: inserting a fenestration product of claim 21 into an opening in the building; securing the fenestration product with a fastener passing through the flange and attaching to the building; and applying the cap to the dome.
 25. The method of claim 24, further comprising injecting a foaming polymer into a joint between the dome and the building.
 26. The method of claim 25, further comprising securing a bezel to the exterior of the building covering the joint.
 27. The method of claim 24, further comprising securing an interior trim part covering at least a portion of the flange. 